Virtual Performance and Emissions Mapping for Diesel Engine Design Optimization 2013-01-0308

This paper builds upon recent publication (SAE Technical Paper 2011-01-1388, 2011, doi:10.4271/2011-01-1388) and outlines the on-going development of an advanced simulator for virtual engine mapping and optimization of engine performance, combustion and emissions characteristics.

The model is further advanced through development of new sub-models for turbulent mixing, multiple injection events, variable injection pressures, engine breathing and gas exchange, as well as particulates formation and oxidation. The result is a simulator which offers engine design and performance data typically associated with 1D thermodynamic engine cycle simulations but with the "physics-based" model robustness usually associated with 3D CFD methods. This combination then enables efficient optimization of engine design with respect to engine performance, combustion characteristics and exhaust gas emissions.

As a demonstration, a detailed method to parameterize (calibrate) the advanced PDF-based model is presented followed by application to three case studies: 1) a concept study of a heavy-duty diesel engine, examining the impact of increased injection pressure and lower compression ratio to meet engine design constraints and Stage IV/Tier 4 exhaust gas emission limits for both NO_x and PM, 2) examining the performance of both the proposed model and 3D-CFD to simulate heat release and exhaust gas emissions in a HSDI diesel engine, 3) performance of the model over a full load-speed map in terms of combustion and NO_x emissions. The results demonstrate the robustness of the model compared to experimental observations and equivalent performance compared to more human resource and CPU cost-intensive 3D-CFD simulations.